Still, throughout the day, GOP lawmakers attempted to paint sanctuary cities as unlawful, and several went so far as to suggest that all four mayors could face criminal prosecution.

The leaders of Boston, Chicago, Denver and New York testified for hours before a largely hostile House committee that accused them of abetting violent migrants.

Republican members of Congress hammered four Democratic mayors about their so-called sanctuary city policies, accusing them of endangering Americans and threatening to prosecute local officials.